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MHT CET 2026 (14 May, Shift 2) · Hydrogen Spectrum & Spectral Series

Hydrogen Spectrum & Spectral Series question from MHT CET 2026 (14 May, Shift 2)

Q6MHT CET 2026 · 14 MAY · SHIFT 2Medium

Hydrogen Spectrum & Spectral Series

If λ1\lambda_1 and λ2\lambda_2 are the wavelengths of the first members of the Lyman and Paschen series respectively then λ1:λ2\lambda_1 : \lambda_2 is

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Answer: (d)

  1. Lyman first line: 1λ1=R(1−14)=3R4\frac{1}{\lambda_1} = R\left(1 - \frac{1}{4}\right) = \frac{3R}{4}, so λ1=43R\lambda_1 = \frac{4}{3R}.
  2. Paschen first line: 1λ2=R(19−116)=7R144\frac{1}{\lambda_2} = R\left(\frac{1}{9} - \frac{1}{16}\right) = \frac{7R}{144}, so λ2=1447R\lambda_2 = \frac{144}{7R}.
  3. λ1λ2=43×7144=7108\frac{\lambda_1}{\lambda_2} = \frac{4}{3} \times \frac{7}{144} = \frac{7}{108}.
  4. So the answer is (d) 7:1087 : 108.
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